Ruiz made frequent appearances on the Food Network, and just opened a restaurant called 'La Cubana' this summer in New York.
The restaurant announced his death on Sunday at the age of 44. The cause is not clear.
A biography on the restaurant's website says Ruiz opened restaurants all over the world in his 25 years in the industry.
Ruiz also built a successful TV and radio career.
La Cubana said it plans to honor Ruiz's memory by establishing a scholarship for aspiring chefs.